Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$244.64	7.288%	$262.4694	$262.47	$262.45	$262.50
Purchase #2	$167.56	6.873%	$179.0764	$179.08	$179.10	$179.10
Purchase #3	$222.67	7.387%	$239.1186	$239.12	$239.10	$239.10
Purchase #4	$183.82	6.666%	$196.0734	$196.07	$196.05	$196.10
Purchase #5	$44.79	4.655%	$46.875	$46.88	$46.90	$46.90
Purchase #6	$138.77	9.255%	$151.6132	$151.61	$151.60	$151.60
Purchase #7	$65.52	12.557%	$73.7473	$73.75	$73.75	$73.70
7 purchase totals =	$1,067.77		$1,148.9733	$1,148.98	$1,148.95	$1,149.00